Heating apparatus for hyperthermia

ABSTRACT

A heating apparatus for hyperthermia utilizes electromagnetic waves for locally heating cancerous cells within a living body. When it is necessary for a plurality of patients to be subjected to hyperthermia treatment at the same time and in parallel with each other, the control of a plurality of electromagentic wave outputs and the control of cooling of the surface of a heated region are effected by a centralized control which employs time-division multiplexing. Thus, it is advantageously possible to efficiently carry out a hyperthermia treatment which is fitting for the condition of each of a plurality of patients.

This is a division of application Ser. No. 121,145 filed Nov. 16, 1987,now U.S. Pat. No. 4,860,770, which is a Divisional of application Ser.No. 756,071 filed on July 17, 1985, now U.S. Pat. No. 4,747,416.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a heating apparatus for hyperthermiaand, more particularly, to a heating apparatus for hyperthermia whichdeteriorates the regenerative functions of cancerous cells by heatingthem with electromagnetic waves, thereby liquidating these cancerouscells.

2. Description of the Prior Art

In recent years, hyperthermia has been given wide attention and papershave been written on hyperthermia, a therapy which deteriorates theregenerative functions of cancerous cells and thereby liquidatessignificant portions of them by applying heat of approximately 43° C.for one or two hours and repeating the treatment at certain intervals.(MICROWAVES. October, 1976).

There are two kinds of hyperthermia therapy: general and local heatingmethods. Three methods have been proposed for local heating: oneutilizes electromagnetic waves, the second uses electric conduction andthe third uses ultrasonic waves.

Researchers have concluded that the optimum temperature for attackingcancerous cells is 43° C. or thereabouts. Temperatures below this willweaken the effects and temperatures above this will damage normal cells.Hyperthermia aims at liquidating without heating normal cells bymaintaining the temperature in a confined narrow range.

However, it has been quite difficult when utilizing conventional meansto keep the temperature of cancerous cells at approximately 43° C. forone or two hours due to the peculiar functions of a living body. Inparticular, heating by electromagnetic waves has been put aside for along time because a significant portion of the electromagnetic waves isabsorbed by the body surface and this method is thus unfit for heatingregions deep within the body. In view of the above-describedcircumstances, the inventors of the present invention have previouslyproposed a heating apparatus for hyperthermia utilizing electromagneticwaves which is provided with a function which enables accurate controlof the temperature of a given heated region in a living body such thatthis temperature is maintained at a predetermined value over a certainperiod of time.

Hyperthermia takes a relatively long period of time (about one hour) fora single treatment and requires that this treatment be repeatedperiodically, which fact involves an unfavorably long overall treatmenttime. In consequence, treating a large number of patients at the sametime requires a correspondingly large number of devices and unfavorablyincreases the cost of installing equipment for treatment.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a heating apparatusfor hyperthermia which is provided with a function which enables thesimultaneous and parallel heating of given regions within the bodies ofa plurality of patients utilizing electromagnetic waves through controleffected from the center of a hyperthermia system, thereby allowing anincrease in the efficiency of the hyperthermia treatment and a reductionin the cost of installing equipment for treatment.

It is another object of the invention to provide a heating apparatus forhyperthermia which is provided with a function which enables heatingtemperatures to be set which are different for each patient even in thecase of simultaneous hyperthermia treatment conducted for a plurality ofpatients by control effected from the center of a hyperthermia systemand which also enables the temperatures set to be optimally controlledover a long period of time and with high accuracy.

It is still another object of the invention to provide a heatingapparatus for hyperthermia which is provided with a function whichenables the prevention of any thermal burn and the alleviation of anypains which patients may suffer by effecting an optimal cooling controlin which the rise in temperature at the surface of the heated region ofa patient, which differs for each patient, is optimally controlled evenin the case of simultaneous hyperthermia treatment conducted for aplurality of patients by control effected from the center of ahyperthermia system.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a general system diagram of a first embodiment of the presentinvention;

FIG. 2 is a perspective view of one example of an applicator;

FIGS. 3 and 4 are flow charts which show the operation of the embodimentillustrated in FIG. 1;

FIG. 5 is a timing chart which shows one example of the time-divisionmultiplexing employed in the invention;

FIGS. 6 and 7 are graphs which show temperature distribution withrespect to depth below the skin of a living body;

FIGS. 8 and 9 are graphs which show the action and operation of theembodiment illustrated in FIG. 1;

FIG. 10 is a general system diagram of a second embodiment of theinvention;

FIGS. 11 and 12 are flow charts which show the operation of theembodiment illustrated in FIG. 10;

FIG. 13 is a general system diagram of a third embodiment of theinvention;

FIGS. 14 and 15 are flow charts which show the operation of theembodiment illustrated in FIG. 13;

FIG. 16 is a general system diagram of a fourth embodiment of theinvention;

FIG. 17 is a flow chart which shows the operation of the embodimentsrespectively illustrated in FIGS. 16 and 20;

FIG. 18 is a flow chart which shows the operation of the embodimentillustrated in FIG. 16;

FIG. 19 is a graph which shows the action and operation of theembodiment illustrated in FIG. 16;

FIG. 20 is a general system diagram of a fifth embodiment of theinvention;

FIG. 21 is a flow chart which shows the operation of the embodimentillustrated in FIG. 20, in cooperation with the flow chart of FIG. 17;

FIG. 22 is a general system diagram of a sixth embodiment of theinvention;

FIG. 23 is a flow chart which shows the operation of the embodimentsrespectively illustrated in FIGS. 22 and 25;

FIG. 24 is a flow chart which shows the operation of the embodimentillustrated in FIG. 22;

FIG. 25 is a general system diagram of a seventh embodiment of theinvention;

FIG. 26 is a flow chart which shows the operation of the embodimentillustrated in FIG. 25, in cooperation with the flow chart of FIG. 23;and

FIGS. 27(1) and 27(2) are timing charts which respectively show otherexamples of a clock pulse train.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First Embodiment

A first embodiment of the present invention will be describedhereinunder with reference to FIGS. 1 to 9.

FIG. 1 is a general system diagram of the first embodiment. In thisembodiment, a heating apparatus for hyperthermia consists essentially ofa microwave generating section 2 which serves as an electromagnetic wavegenerating section, a control section 4 which includes control means,and a microwave irradiating section 6.

The microwave generating section 2 is composed of: magnetrons 8 whichserve as electromagnetic wave generating means for simultaneouslyirradiating three patients (the number of patients assumed is the samethroughout the embodiments described hereinafter) with electromagneticwaves; directional couplers 10 which are disposed on the respectiveoutput sides of the magnetrons 8; diodes 12 which serve as sensors fordetecting the respective output levels of the magnetrons 8 through therespective directional couplers 10; and power control units 14 whichadjust the respective outputs of the magnetrons 8. Each of the powercontrol units 14 is adapted to adjust the output of the associatedmagnetron 8 by changing the anode voltage of the magnetron 8 which iscontrolled by a thyristor. Each of the directional couplers 10 has afunction of isolating incident and reflected waves from each other andindividually taking them out. The electromagnetic waves taken out by thedirectional couplers 10 are respectively detected by the diodes 12 andconverted into voltages, each of which is then delivered to a maincontrol unit 16 in the control section 4 through an analog-to-digitalconverter, not shown, (referred to simply as an "A/D converter",hereinafter).

The main control unit 16 obtains a difference between the respectivepower level values of the incident and reflected waves taken out,thereby calculating the power level of the microwave which is to beeffectively supplied to each of the applicators 18 (described later)provided in the microwave irradiating section 6. The main control unit16 controls the output of each of the magnetrons 8 on the basis of theresult of this calculation.

The microwave irradiating section 6 in this embodiment is composed of:applicators 18 each irradiating a living body 26 with microwaves; acooler 20 which cools a coolant for cooling the opening side of eachapplicator 18, that is, the surface of the body 26; a pump 22 whichrecirculates the coolant cooled by the cooler 20; and a branchingcircuit 24 for supplying the coolant to each applicator 18. Themicrowave irradiating section 6 further includes internal temperaturesensors 28 which serve as internal temperature detecting means and eachwhich detects the temperature of cancerous cells inside thecorresponding body 26, each internal temperature sensor 28 being stuckinto a part of the body 26 where the hyperthermia treatment is takingplace. Illustration of the portions of microwave irradiating section 6for the other two patients is omitted (the same is the case with each ofthe embodiments described hereinafter).

Each applicator 18 is an antenna which is, as shown in FIG. 2, broughtinto close contact with the surface of the corresponding body 26 andirradiates the body 26 with electromagnatic waves for the purpose ofheating targeted cancerous cells. Each applicator 18 has a coolingmember 30 provided on the surface thereof which contacts the surface ofthe body 26 in order to prevent the skin thereof from being thermallyburnt which would be caused by the heat generated as the result ofdielectric losses in the skin at the area of contact of the body 26.Each of the cooling members 30 is provided with a pipe 32 for passingwater which is employed as a coolant (the same is the case with each ofthe embodiments described hereinafter). In consequence, the water whichis cooled in the cooler 20 is forcedly recirculated through each coolingmember 30 by the operation of the pump 22, thereby cooling the openingside of each applicator 18, that is, the surface of the correspondingbody 26.

Each internal temperature sensor 28 detects the temperature of cancerouscells, and the output of the corresponding magnetron 8 is adjusted bythe main control unit 16 on the basis of information obtained by thesensor 28.

On the other hand, the control section 4 is composed of: an input/outputunit 34 to which information is input by an operator and which informsthe operator of treatment conditions; and the above-described maincontrol unit 16 which constitutes the center of this system and bothcontrols and manages input/output devices in accordance with programsand data respectively stored in program and data memory devices.

The main control unit 16 is arranged such that three systems ofinformation about the three patients are input to and output from themain control unit 16. Since the three systems of information are inputand output while being successively interchanged with each other by amultiplexer provided in the main control unit 16, it is possible for asingle A/D converter and a single D/A converter (which are not shown) toprocess input and output information, respectively.

More specifically, the main control, unit 16 is fed with informationobtained by the respective sensors 28 for the three patients via the A/Dconverter while successively interchanging the information by means ofthe multiplexer. On the basis of the thus input information and theinformation which is delivered from the input/output unit 34 by theoperator, the main control unit 16 controls the output of each magnetron8 by outputting information via the D/A converter while successivelyinterchanging the output information by means of the multiplexer so thatthe temperature of cancerous cells (referred to simply as the "internaltemperature", hereinafter) inside each body 26 is maintained at adesired value. In addition, the main control unit 16 delivers thevarious above-described information to the input/output unit 34 in orderto apprise the operator of the heating conditions of each body 26.

The general operation of the above-described heating apparatus will bedescribed hereinunder with reference to FIGS. 3 to 5. It is to be notedthat, in the following description, a target value for the temperatureof the surface of each body 26 (referred to simply as the "surfacetemperature", hereinafter) whic contacts the corresponding applicator 18is set at 20° C., while a target value for the internal temperature isset at 43.5° C.

First, the cooler 20 is started (Step 40 shown in FIG. 3), and after thewater has been sufficiently cooled, the pump 22 is started (Step 50 inFIG. 3). Then, the operator predetermines a maximum output level foreach magnetron 8 in accordance with the depth below the skin of thecancerous cells in the body of each patient and sets the level from theinput/output unit 34 (Step 60 in FIG. 3). Then, the operatorpredetermines a maximum output level for each magnetron 8 in accordancewith the depth below the skin of the cancerous cells in the body of eachpatient and sets the level from the input/output unit 34 (Step 60 inFIG. 3).

The reason why a maximum output of each magnetron 8 is set in accordancewith the depth of the cancerous cells is as follows. As the microwaveoutput is increased the temperature peak in heating is shifted towardthe surface of a body, whereas as the microwave output is decreased thetemperature peak is shifted toward the inside of the body since in sucha case the heat gradually penetrates into the body. For this reason, itis necessary for a maximum output of each magnetron 8 to be set at avalue which fits the condition of the corresponding patient. FIG. 6 is agraph which represents the results of experiments carried out on aphantom model which approximated to a living body. The graph showscomparison between a temperature distribution (A) obtained byirradiating the phantom model with a microwave of 2,450 MHz on the basisof a reference quantity, and a temperature distribution (B) obtained byirradiating the phantom model with a microwave whose output was set bysubtracting 3 dB from that reference quantity. Such a frequency band ishighest in the frequency regions for hyperthermia, and consequently, therange of temperature peaks is limited to the surface layer of thephantom mode. It may nevertheless be understood that the temperaturedistribution (B) has a temperature peak at a portion which is about 0.25cm deeper than that of the temperature distribution (A). However, areduction in the microwave output requires a correspondingly increasedtime to heat cancerous cells up to a target temperature. FIG. 7 is agraph which shows changes in temperature of a heated portion measuredfor each predetermined period of time. The curves in the graph representheating characteristics in this embodiment.

Setting of a maximum output for each magnetron 8 in operation iseffected by the main control unit 16 on the basis of informationdelivered from the corresponding directional coupler 10. Morespecifically, the main control unit 16 obtains an effective microwaveoutput which is to be supplied to each applicator 18 in accordance withthe difference between the respective power levels of the incident andreflected waves detected by the corresponding directional coupler 10.The main control unit 16 then matches the thus obtained microwave outputwith a value which is set by the operator from the input/output unit 34,thereby setting an optimal maximum microwave output. In this case,however, a maximum microwave output may previously be set at apredetermined level by employing a phantom model. Maximum microwaveoutputs for the three patients are herein represented by P₁, P₂ and P₃,respectively.

Next, the operator sets a heating time for each of the patients (Step 70in FIG. 3). The reason why a heating time is set for each individualpatient is that it is necessary for each treating time to be determinedin accordance with the actual condition of the patient concerned.

After these initial values have been set as described above, eachpatient is subjected to microwave irradiation (Steps 80 and 90 in FIG.3). A detailed flow chart for this microwave irradiation is shown inFIG. 4.

The control program shown in FIG. 4 is executed by time-divisionmultiplexing in synchronism with clock pulses (shown in FIG. 5)generated in the main control unit 16.

More specifically, when a clock pulse (e.g., 1) is input, the controlprogram shown in FIG. 4 is processed within a very short period of time,that is, Δh shown in FIG. 5, and magnetron output for each microwaveirradiation period is thereby determined by a judgement made by the maincontrol unit 16 which functions in accordance with the control program.After microwave irradiation has been effected with the thus determinedmagnetron output for a predetermined period of time (e.g., H in FIG. 5)(there are, as a matter of course, cases where the judgement made by themain control unit 16 is that no microwave irradiation is to be carriedout), the processing of the control program is executed again insynchronism with a subsequent clock pulse 1. Thus, treatment for asingle patient is carried out through a series of processings in thisway. As regards the other two patients, the control program is processedin synchronism with a clock pulse 2 or 3. Thus, it is possible for aplurality of terminal devices to be controlled by a single control unit,and even a plurality of patients can be subjected to hyperthermiatreatment at substantially the same time and in parallel with eachother.

The flow chart shown in FIG. 4 will now be described in detail. When aclock pulse (e.g., 1) is input, the output of the magnetron 8 for afirst patient is cut off in order to measure the internal temperature ofthis patient (Steps 100 and 110 in FIG. 4). No microwave irradiation iscarried out during the measurement of internal temperature. This isbecause if microwave irradiation is continued, the internal temperaturesensor 28 inserted into the body of the patient is affected by themicrowave, which fact leads to errors in measurement of the internaltemperature. After the internal temperature has been measured, ajudgement is made (Step 120 in FIG. 40) as to whether or not the heatingtime has reached the value previously set (see Step 70 in FIG. 3). IfYES, the treatment for the first patient alone is ended, and the processshifts to steps for treating the other patients (Step 130 in FIG. 4;Step 90 in FIG. 3). More specifically, the multiplexer in the maincontrol unit 16 is switched over, and input/output ports of the maincontrol unit 16 are changed over to the internal temperature sensors 28and the power control units 14 for the other patients (Step 90 in FIG.3), thus executing processing for the other patients.

If the judgement (Step 120 in FIG. 4) indicates that the heating timehas not yet reached the set value, a judgement is made (Step 140 in FIG.4) as to whether or not the internal temperature (the temperature ofcancerous cells) measured beforehand is higher than the set value (43.5°C.) which has previously been input by the operator. When the internaltemperature is lower than the set value, the main control unit 16 givesinstructions to the power control unit 14 concerned whereby the outputsetting for the corresponding magnetron 8 is stepped up by one degree.However, the arrangement is such that, even when this control process isrepeated for each clock pulse, the initially set maximum input power isnot exceeded (see Steps 150 and 160 in FIG. 4). On the basis of thisnewly set value, microwave irradiation is effected (Step 170 in FIG. 4),and heating for hyperthermia is continued until a subsequent clock pulse1 occurs. More specifically, the microwave irradiation and themeasurement of internal temperature are repeated until the internaltemperature becomes higher than the set value, and the output settingvalue for the magnetron 8 is stepped up by one degree every time thiscontrol process is executed utilizing the period of time during whichthe internal temperature is measured in synchronism with the clockpulse. In consequence, subsequent microwave irradiation is effected onthe basis of the stepped-up output setting value.

On the other hand, when the judgement (Step 180 in FIG. 4) indicatesthat the internal temperature becomes higher than the set value as aresult of the above-described microwave irradiation, measurement of theheating time is immediately started by the main control unit 16 (Step180 in FIG. 4). At this time, since the internal temperature (thetemperature of cancerous cells) is slightly higher than the set value,the output setting value for the magnetron 8 is stepped down by onedegree for the purposes of heating in a subsequent period (Step 180 inFIG. 4). The output of the magnetron 8 is continuously cut off until asubsequent clock pulse 1 occurs (Step 200 in FIG. 4), and if theinternal temperature is judged to be lower than the set value in thecontrol process subsequently repeated, the output of the magnetron 8 isturned on through the aforementioned Steps 160 and 170 (see FIG. 4).This repetition of the control process is effected within a very shortperiod of time by the above-described time-division multiplexing,whereby a highly accurate heating for hyperthermia is continued over along period of time, as shown in FIG. 8 which will be described later.

In this case, the main control unit 16 is programmed such that, whenrepeating the control program shown in FIG. 4, the main control unit 16actually executes only those steps which need to be executed for eachrepetition of the control program. For example, a program is arrangedsuch that a first control is executed from Step 170 in FIG. 4 "Output ofMagnetron 8 ON (at a maximum output, in this case)", and if Step 180 inFIG. 4 "Start Heating Time Measurement" is once executed, this Step 180is skipped in the control effected thereafter. In addition, whentreatment for all the patients has been completed, a display lamp (notshown) is turned on, and the drive of the apparatus is suspended by theoperator.

FIG. 8 shows changes with time in the internal temperature (thetemperature of cancerous cells) of a single patient measured during eachmicrowave irradiation period, each non-irradiation period and eachinternal temperature measuring period (during which the control programshown in FIG. 4 is processed), together with changes in the output ofthe associated magnetron 8.

In FIG. 8, each of the intervals in which the internal temperature curveascends corresponds to a microwave irradiation period, while each of theintervals Δh in which the temperature curve descends corresponds to aperiod during which an internal temperature measuring operation iseffected in synchronism with one clock pulse as shown in FIG. 5. Duringeach of the internal temperature measuring periods, the output of themagnetron 8 is zero (see Step 100 in FIG. 4). The point B in FIG. 8represents a point of time at which the internal temperature firstexceeds the set value as the result of the microwave irradiation by amaximum output (P₁) of the magnetron 8 and the measurement of theheating time is hence started. The above-described heating time iscounted from this point B. The length of the period of time after theinternal temperature has reached 43° C. or thereabouts is one of theprimary factors used in reaching a decision as to whether or not it ispossible to effectively liquidate cancerous cells. For this reason, theheating time is set in accordance with the particular condition of eachpatient (Step 70 in FIG. 3).

Thereafter, instructions are continuously given to cut off the output ofthe magnetron 8 during each internal temperature measuring period untilthe internal temperature reaches 43.5° C. or below (see Steps 100 and200 in FIG. 4). During this period (the period between B and C in FIG.8), the output of the magnetron 8 which is to be applied subsequently isnewly set, and at the point of time when the internal temperaturereaches 43.5° C. or below, microwave irradiation is resumed (during theperiod between C and D in FIG. 8). The time I between B and Ccorresponds to, for example, the time I which is shown in FIG. 5. Duringthe period between C and D in FIG. 8, the internal temperature curve issmaller in terms of the degree of slope than that between A and B sincethe output setting value for the magnetron 8 has been lowered.

In the case where the internal temperature does not reach 43.5° C. inthe next microwave irradiation (e.g., during the period between E and Fin FIG. 8) since the output setting value for the magnetron 8 has beenexcessively lowered during an internal temperature measuring period, themagnetron output is stepped up during the next internal temperaturemeasuring period (e.g., the period between F and G in FIG. 8) as shownin Step 160 in the flow chart of FIG. 4. In consequence, the degree ofslope of the internal temperature curve is increased again (during theperiod between G and H in FIG. 8). By virtue of such repetition ofcontrol, it is possible to obtain an internal temperature control whichinvolves substantially no ripple in heating for each of the patients.Since an internal temperature above 45° C. adversely affects normalcells, it is necessary for the maximum output of the magnetron 8 and theirradiation time to be set such that the internal temperature does notexceed 45° C. at any time during the heating treatment.

FIG. 9 shows changes in the internal temperature with time in the casewherein the maximum output of the magnetron 8 is set at a relatively lowvalue (P₂) since targeted cancerous cells are present in a relativelydeep part of the body of the patient.

As has been described above, it is possible according to the firstembodiment to effect a highly accurate control such that the internaltemperature is maintained at a set value or at values in close proximityto it over a long period of time, and it is possible for a plurality ofpatients to be subjected to hyperthermia treatment at the same time andin parallel with each other, which fact advantageously leads to afurther increase in treatment efficiency. Since in this case a singlemain control unit is conveniently used in common, it is favorablypossible to reduce the cost of installing treatment equipment as well asto permit a batch-type control from the center of the hyperthermiasystem, thus improving the controllability. Moreover, when a pluralityof patients are simultaneously subjected to hyperthermia treatment,control is effectively executed for each individual patient. It istherefore advantageously possible for various patients to beindividually subjected to treatments which are individually suitableeven when the conditions of these patients differ from one another, forexample, one for which the internal temperature curve shown in FIG. 8 isfitting and another for which the internal temperature curve in FIG. 9is fitting.

Second Embodiment

A second embodiment of the invention will now be described withreference to FIGS. 10 to 12, in which the same constituent elements asthose in the first embodiment are denoted by the same reference numerals(the same is the case with each of the embodiments describedhereinafter).

The feature of the second embodiment resides in the fact that the flowrate of the coolant is controlled for each of the patients in such amanner that the surface temperature (the skin temperature) of a heatedregion of the body of each patient is maintained in the approximatevicinity of a predetermined value and that the respective outputs of aplurality of electromagnetic wave generating means are controlled by asingle main control unit while being interchanged with each other insuch a manner that the outputs are controlled for individual patients,explained in detail in the description of the first embodiment. Thus,the second embodiment aims at effectively treating a plurality ofpatients at the same time and in parallel with each other whilepreventing the patients from being thermally burned.

To this end, each of the valves 210 and each of the flow rate sensors212 are, as shown in FIG. 10, provided between the branching circuit 24in the microwave irradiating section 6A and the inlet side of thecooling member 30 of each applicator 18, the valves 210 constitutingrespective essential portions of flow rate adjusting means whichrespectively adjust the flow rates of the coolant for individualpatients, and the flow rate sensors 212 being adapted to detect the flowrate of the coolant for each patient. Additionally, valve control units216 are provided for controlling the respective valves 210. Coolanttemperature sensors 214 are also additionally provided on the respectiveoutlet sides of the cooling members 30, the sensors 214 serving ascoolant temperature detecting means each of which detects thetemperature of the coolant which is to be supplied to each coolingmember 30. Information detected by each flow rate sensor 212 and thatdetected by each coolant temperature sensor 214 are delivered to themain control unit 16 in the control section 4 through respective A/Dconverters (not shown). These pieces of information serve as principalreference values which are employed in the main control unit 16 tocontrol each valve 210. More specifically, the degree of opening of eachvalue 210 is determined by the main control unit 16 on the basis of theinformation detected by the corresponding flow rate sensor 212 andcoolant temperature sensor 214 and is controlled by the correspondingvalve control unit 216. In consequence, the flow rate of the coolant tobe supplied to the cooling member 30 of each applicator 18 is controlledin accordance with the degree of opening of the corresponding valve 210,and the surface temperature of the body of each patient is therebyadjusted.

The arrangement of the other portion of the second embodiment is thesame as that of the first embodiment.

The following is a description of the operation of the second embodimentwith reference to FIGS. 11 and 12, in which steps which represent thesame operations as those in the first embodiment are denoted by the samereference numerals (the same is the case with each of the embodimentsdescribed hereinafter). Setting values for a target surface temperature(20° C.) and a target internal temperature (43.5° C.) are also the sameas those in the first embodiment.

First, the cooler 20 is started (Step 40 in FIG. 11), and after thecooling water (coolant) has been sufficiently cooled, the pump 22 isstarted (Step 50 in FIG. 11). Then, the degree of opening of each valve210 is controlled on the basis of the information detected by thecorresponding flow rate sensor 212 such that the amount of cooling waterrecirculating is minimized (Steps 51 and 52 in FIG. 11). Thereafter, ina manner similar to that in the first embodiment, a maximum output ofeach magnetron 8 is set (Step 60 in FIG. 11), and a heating time foreach patient is set by the operator (Step 70 in FIG. 11).

Then, control is effected for each patient in accordance with a flowchart shown in FIG. 12. This control is carried out in synchronism withthe clock pulses shown in FIG. 5 by time-division multiplexing in amanner similar to that in the first embodiment (the same is the casewith each of the embodiments described hereinafter).

when a clock pulse (e.g., 1) is input, the output of the magnetron 8 iscut off in a manner similar to that in the first embodiment for thepurpose of preventing the occurrence of errors in measuring temperatures(Step 100 in FIG. 12), and the surface temperature and the internaltemperature are measured (Step 111 in FIG. 12). Then, a judgement ismade as to whether or not the heating time set beforehand (see Step 70in FIG. 11) has been reached (Step 120 in FIG. 12). If YES, thetreatment for the patient concerned alone is ended, and the processshifts to the control for treating another patient in a manner similarto that in the first embodiment (Step 130 in FIG. 12; Step 90 in FIG.11). On the other hand, if the set heating time has not yet beenreached, a judgement is made (Step 121 in FIG. 12) as to whether or notthe surface temperature which has been previously measured is higherthan the set value (20° C.) which has been input by the operator. IfYES, the main control section 16 instructs the valve control unit 216 toincrease the degree of opening of the valve 210 by one step in order tolower the surface temperature (Step 191 in FIG. 12), while the output ofthe magnetron 8 is kept cut off (Step 200 in FIG. 12). Then, themultiplexer in the main control unit 16 is switched over in such amanner that the input/output ports of the main control unit 6 arechanged over for another patient (Step 90 in FIG. 11), whereby theprocessing for the next patient is successively executed. Then, when asubsequent clock pulse 1 is input, judgement on the surface temperatureis made again (Step 121 in FIG. 12) through the above-described Steps100, 111 and 120. If the surface temperature has lowered below the setvalue during a certain period of time between the processings of Step121 in the last control process and in the present control process, thevalve 210 is closed by one step so that the surface of the body of thepatient is not excessively cooled (it is, however, necessary for theflow rate of water to be high enough to maintain a minimum amount ofwater for recirculation), and the internal temperature (the temperatureof cancerous cells) is then adjusted (Steps 122 and 140 in FIG. 12).

When the internal temperature of the body of the patient is lower thanthe set value (43.5° C.), microwave irradiation is effected (Step 170 inFIG. 12) through Steps 150 and 160 in a manner similar to that in thefirst embodiment. The heating is continued until a subsequent clockpulse 1 occurs. When the internal temperature becomes higher than theset value, the measurement of heating time is started (Step 180 in FIG.12), and microwave irradiation and the measurement of internaltemperature are repeated in a manner similar to that in the firstembodiment. However, if the surface temperature exceeds the set valueduring the repetition of the microwave irradiation and the measurementof internal temperature (Step 121 in FIG. 12), Step 191 in FIG. 12wherein the valve 210 is opened by one step and Step 200 in FIG. 12wherein the output of the magnetron 9 is cut off are repeatedlyexecuted.

In the control in which the process proceeds through Steps 122, 140,180, 190 and 191, the output of the magnetron 8 is stepped down by onedegree (Step 190 in FIG. 12) and then the valve 210 is opened by onestep (Step 191 in FIG. 12). This is done because it is necessary tocompensate for the degree of opening of the valve 210 which has beenclosed by one step in Step 122 shown in FIG. 12. In other words, whenthe internal temperature (the temperature of cancerous cells) has becomehigher than the set value, it is necessary to lower the surfacetemperature so that the internal temperature comes close to the setvalue as quickly as possible.

The other operations of the second embodiment are the same as those ofthe first embodiment, and the heating characteristic curves respectivelyshown in FIGS. 8 and 9 may be applied to the second embodiment in amanner similar to that in the first embodiment.

In the second embodiment, the internal temperature and the surfacetemperature are respectively set at desired values for each of thepatients in such a manner that the control of these temperatures ischanged over from one patient to another. Accordingly, the effectsoffered by the second embodiment are equivalent to those offered by thefirst embodiment. In addition, it is possible to efficiently prevent therise in the surface temperature of the heated region of a body. Thus, itis advantageously possible to effectively alleviate any pain, caused by,for example, thermal burn, which the patient may suffer during thehyperthermia treatment.

Third Embodiment

A third embodiment of the invention will be described hereinunder withreference to FIGS. 13 to 15.

This embodiment aims at effecting a simultaneous and parallel treatmentfor a plurality of patients and controlling cooling of the surface of abody at a heated region in a manner similar to that in the secondembodiment. This embodiment adopts a method of cooling the surface of abody in which the temperature of a coolant (water) is controlled.

More specifically, a microwave irradiating section 6B is, as shown inFIG. 13, provided with coolers 218 respectively serving as coolantcooling means each of which cools the coolant for the corresponding oneof three patients, and tcooling control circuits 220 each controllingthe corresponding cooler 218 thereby to adjust the temperature of thecoolant. The coolant cooled in each cooler 218 is recirculated throughthe cooling member 30 of the applicator 18 for each patient by theoperation of the corresponding pump 22. Additionally, a coolanttemperature sensor 214 serving as a coolant temperature detecting meanswhich detects the temperature of the coolant is provided on the outletside of each cooling member 30. Temperature information detected by eachcoolant temperature sensor 214 is delivered to the main control unit 16in the control section 4 as illustrated. Accordingly, the main controlunit 16 obtains the surface temperature of the body 26 which is incontact with each applicator 18 on the basis of the deliveredtemperature information and delivers a control signal to thecorresponding cooling control circuit 220 such that the surfacetemperature is maintained at a set value. Thus, the cooling capacity ofeach cooler 218 is controlled as described above.

The arrangement of the other portion of this embodiment is the same asthat of the second embodiment.

The general operation and function of third embodiment will now beexplained with reference to FIGS. 14 and 15. It is to be noted that theset value (43.5° C.) for the internal temperature and the set value (20°C.) for the surface temperature are the same as those in the first andsecond embodiments.

First, each cooler 218 is started (Step 40 in FIG. 14), and after thewater has been sufficiently cooled, each pump 22 is started (Step 50 inFIG. 14). Then, the operator sets a maximum output for each magnetron 8(Step 60 in FIG. 14) and also a heating time which is matched with thecondition of each patient (Step 70 in FIG. 14) from the same viewpointas that in the first embodiment.

When the above-described initial setting has been completed, changeovercontrol for three patients is effected by time-division multiplexing insynchronism with the clock pulses (see FIG. 5) generated in the maincontrol unit 16 (Steps 82 and 90 in FIG. 14).

More specifically, control for each patient is carried out by the maincontrol unit 16 in a manner such as that shown in FIG. 15. The controloperation shown in FIG. 15 is generally the same as that in the secondembodiment (see FIG. 12) except for the following two steps:

(1) When the surface temperature of the heated part is lower than theset value (that is, if NO is the result of the judgement made in Step121 in FIG. 15), the output (cooling capacity) of the cooler 218 isstepped down by one degree (Step 123 in FIG. 15) in order to prevent thesurface of the body of the patient from being excessively cooled (inthis case, the output of the cooler 218 may be cut off, since thecoolant is continuously recirculated by the pump 22 and there istherefore no fear of the surface layer of the body of the patient beingthermally burned). Then, a subsequent judgement is made in Step 140.

(2) When the surface temperature is higher than the set value (that is,if YES is the result of the judgement in Step 121 in FIG. 15), the maincontrol unit 16 instructs the output of the cooler 218 to be stepped upby one degree in order to lower the surface temperature (Step 192 inFIG. 15). Also when the measurement of heating time is started (Step 180in FIG. 15) and the power level of the magnetron 8 is stepped done byone degree (Step 190 in FIG. 15), the output of the cooler 218 isstepped up by one degree (Step 192 in FIG. 15) in order to compensatefor the cooling capacity of the cooler 218 which has been stepped downby one degree in Step 123 in FIG. 15.

Thus, in this embodiment the temperature of the coolant is employed asone of the control variables used to control the surface temperature ofthe heated region of the body of each patient, whereas in the secondembodiment the flow rate of the coolant is employed. The heatingcharacteristic curves respectively shown in FIGS. 8 and 9 may be alsoapplied to this embodiment.

With the above-described arrangement, it is also possible to obtainadvantageous effects which are substantially equivalent to that offeredby the second embodiment. Since the coolers 218 are provided forindividual patients, it is possible to effect a more precise individualcontrol of the surface temperature. Thus, it is advantageously possibleto expedite the hyperthermia treatment.

It is to be noted that this embodiment can be satisfactorily put intopractical use even if the coolant temperature sensors 214 serving ascoolant temperature detecting means are removed in accordance with need.

Since a relatively low frequency is employed to heat a relatively deeppart of a living body, it is possible for each of the above-describedembodiments to employ an oscillator which is suitable for oscillatingmicrowaves of relatively low frequencies and a linear amplifier in placeof each of the magnetrons employed in the above-described embodiments.In such a case, the power level of the oscillator is varied by employinga thyristor in a manner similar to that in the case where each magnetronis controlled by a thyristor, or by changing the amplification degree orgain of the linear amplifier. It is, however, necessary to employ anisolator for the purpose of eliminating adverse effects exerted byreflected waves.

Fourth Embodiment

A fourth embodiment of the invention will now be described withreference to FIGS. 16 to 19.

This embodiment aims at subjecting a plurality of patients tohyperthermia treatment at the same time and with high efficiency bycontrolling the output of each of the electromagnetic wave generatingmeans through an ON/OFF control and controlling the flow rate of thecoolant.

Referring first to FIG. 16 which shows the arrangement of the fourthembodiment, a microwave generating section 2A which serves as anelectromagnetic wave generating section is composed of: the magnetrons 8respectively serving as electromagnetic wave generating means whichgenerate electromagnetic waves for respective patients; power sources222 each controlling the corresponding magnetron 8; and switches 224serving as respective essential portions of ON/OFF switching means eachof which ON/OFF controls the corresponding power source 222. Each switch242 is controlled by the main control unit 16 in the control section 4as illustrated. More specifically, the switches 224 are turned ON or OFFin accordance with predetermined instructions given from the maincontrol unit 16, and the power sources 222 which respectively associatedwith the switches 224 are turned ON or OFF in response to the respectiveoperations of the switches 224. In consequence, the magnetrons 8 areindividually ON/OFF controlled.

On the other hand, information detected by each internal temperaturesensor 28 and that detected by each flow rate sensor 212 are deliveredto the main control unit 16 at all times. The main control unit 16ON/OFF controls each magnetron 8 and adjusts the degree of opening ofeach valve 210 on the basis of the information detected and deliveredthereto and instruction information input by the operator as describedabove.

The arrangement of the other portion of each of the main control unit 4and the microwave irradiating section 6C is the same as that of thesecond embodiment. However, the temperature sensor 214 which is disposedon the outlet side of each cooling member 30 in the second embodiment isnot provided in this embodiment.

The following is a description of the general operation of thisembodiment with reference to FIGS. 17 to 19. It is to be noted thattarget values for the internal temperature and the surface temperatureare respectively set at 43° C. and 20° C.

First, the cooler 20 is started (Step 40 in FIG. 17), and after thecooling water has been sufficiently cooled, the pump 22 is started (Step50 in FIG. 17). Then, the main control unit 16 controls the degree ofopening of each valve 210 such that the amount of cooling waterrecirculating is minimized in a manner similar to that in the secondembodiment (Steps 51 and in FIG. 17). In addition, a heating time whichis matched with the condition of each patient is set to the main controlunit 16 by the operator from the input/output unit 34 (Step 70 in FIG.17).

After the above-described initial setting has been completed,hyperthermia treatment for three patients is started on the basis of thetime-division multiplexing control effected by the main control unit ina manner similar to each of the above-described embodiments (Steps 83and 90 in FIG. 17).

The control process for each of the three patients is shown in FIG. 18.When a clock pulse 1 shown in FIG. 5 is input, instruction is given tocut off the output of the magnetron 8 for, for example, a first patient(Step 100 in FIG. 18), and the measurement of internal temperature iseffected on the basis of the information detected by the internaltemperature sensor 28 (Step 110 in FIG. 18).

Then, a judgement is made as to whether or not the heating timepreviously set has been reached (Step 120 in FIG. 18). If YES, thehyperthermia treatment for the first patient is ended, and the processshifts to the heating control for a second patient (step 13 in FIG. 18;Step 90 in FIG. 17). However, if the judgement made in Step 120indicates that the heating time has not yet been reached, then ajudgement is made as to whether or not the internal temperature ishigher than the set value (43° C.) (Step 140 in FIG. 18).

When the internal temperature (the temperature of cancerous cells) islower than the set value, the valve 210 is closed by one step (Step 122in FIG. 18), whereby the surface temperature is raised (however, in thiscase also, it is necessary for the flow rate of cooling water to be highenough to maintain a minimum amount of cooling water for recirculationin order to prevent the surface of the body of the patient from beingthermally burned). This is done because it is also necessary to effect atemperature adjustment at the surface of the patient body so that thetemperature of cancerous cells inside the body quickly reaches the setvalue. Then, the main control unit 16 instructs the output of themagnetron 8 to be turned ON (Step 170 in FIG. 18), whereby microwaveirradiation is effected by a predetermined output of the magnetron 8 fora predetermined period of time (see H in FIG. 5). During this microwaveirradiation period, the multiplexer is switched over to effect controlsimilar to the above for each of the second and third patients. When asubsequent clock pulse 1 occurs, the control for the first patient isresumed.

When the internal temperature becomes higher than the set value duringthe repetition of a loop similar to the above (that is, if the answer ofthe judgement made in Step 140 in FIG. 18 is YES), the measurement ofheating time is started by the main control unit 16 (Step 180 in FIG.18), and the valve 210 is opened by one step (Step 191 in FIG. 18).Thus, the surface temperature is lowered, and the internal temperatureis also thereby adjusted at the surface of the body of the patient sothat the temperature of cancerous cells quickly returns to the setvalue. During this adjustment period, the magnetron 8 is turned OFF(Step 200 in FIG. 18), and processing for the other patients is carriedout in a manner similar to the above.

The above-described control is effected for each of the patients, andheating at a temperature in the vicinity of 43° C. is started from apoint of time when the internal temperature first exceeds the set value(see the point C in FIG. 19). This heating is continued until theheating time set by the operator has elapsed.

FIG. 20 shows one example of the above-described heating characteristiccurves. In this Figure, the reference symbol A represents how theinternal temperature (the temperature of cells) rises, while the symbolB represents how the output of the magnetron 8 is ON/OFF controlled(showing either one of the ON and OFF states). The point C, as describedabove, represents a point of time when the measurement of heating timeis started in response to the detection of the fact that the internaltemperature has reached the point of exceeding the set value as theresult of the microwave irradiation. The section between C and D shows achange in the internal temperature when the output of the magnetron 8 isOFF, while the section D and E shows a change in the internaltemperature when the output of the magnetron 8 is ON. Thus, it ispossible for the internal temperature to be quickly raised to the setvalue. Even when the internal temperature exceeds the set value, theinternal temperature can be quickly lowered, since it is possible tocool the surface of the body of the patient. Accordingly, it isadvantageously possible for the internal temperature to be constantlymaintained at approximately 43° C.

As has been described above, this embodiment offers advantageous effectswhich are substantially equivalent to those offered by the secondembodiment. Since the output of each of the electromagnetic wavegenerating means is simply ON/OFF controlled without employing anycomplicated output control means, the arrangement is simplifiedcorrespondingly. Accordingly, it is advantageously possible to improvethe controllability and reduce the cost of installing treatmentequipment.

Fifth Embodiment

A fifth embodiment of the invention will be described hereinunder withreference to FIGS. 17 and 20 and 21.

This embodiment aims at precisely controlling also the surfacetemperature in addition to the object of the fourth embodiment.

To this end, a coolant temperature sensor 214 (one which is the same asthat employed in the second embodiment) is additionally provided on theoutlet side of the cooling member 30 of each applicator 20 as shown inFIG. 20, the sensor 214 serving as a coolant temperature detecting meanswhich measures the temperature of cooling water. Information detected byeach coolant temperature sensor 214 is delivered to the main controlunit 16. The arrangement of the other portion of this embodiment is thesame as that of the fourth embodiment.

General control of this embodiment is effected in accordance with flowcharts respectively shown in FIG. 18, which shows the operation of thefourth embodiment, and FIG. 21. In this case, target values for theinternal temperature and the surface temperature are respectively set at43° C. and 20° C.

According to the above-described flow charts, the following functionsare added to those of the fourth embodiment:

(1) The surface temperature of the body of each patient is measured(Step 111 in FIG. 21).

(2) A judgement is made as to whether or not the surface temperature ishigher than the set value (20° C.) (Step 212 in FIG. 21), and the degreeof opening of the corresponding valve 210 is adjusted by feedbackcontrol (Steps 122 and 191 in FIG. 21).

Since this embodiment is arranged and operated as described above, it ispossible to obtain advantageous effects which are equivalent to thoseoffered by the fourth embodiment. Since the surface temperature ismonitored at a regular predetermined timing for effecting a precisecontrol, it is possible for the surface temperature to be maintained ata predetermined value where the patient suffers no pain. Thus, it isadvantageously possible to prevent the occurrence of any thermal burn orthe like.

Sixth Embodiment

A sixth embodiment of the invention will now be described with referenceto FIGS. 22 to 24.

This embodiment aims at effecting a simultaneous and parallelhyperthermia treatment for a plurality of patients by simply ON/OFFcontrolling the output of each of the electromagnetic wave generatingmeans and by controlling the temperature of the coolant.

Referring first to FIG. 22, the arrangement of this embodiment is asfollows.

(1) The microwave generating section 2A has the same arrangement as thatof the fifth embodiment (see FIG. 20).

(2) The microwave irradiating section 6D is arranged in a manner similarto that of the third embodiment. However, this section 6D is notprovided with the coolant temperature sensors 214 (see FIG. 13).

(3) The main control unit 16 in the control section 4 is adapted tocontrol each cooling control circuit 220 and each switch 224 on thebasis of information detected by the corresponding internal temperaturesensor 28 inserted into the body 26 and instructions given by theoperator via the input/output unit 34.

The following is a description of the general operation of thisembodiment. It is to be noted that target values for the internaltemperature and the surface temperature are respectively set at 43° C.and 20° C. Steps which respectively show the same operations as those ineach of the above-described embodiments are denoted by the samereference numerals.

First, in manner similar to the above, each cooler 218 is started (Step50 in FIG. 23). Then, the operator sets a heating time for each of thepatients (Step 70 in FIG. 23). In the main control unit 16, controloperations for individual patients are effected while being successivelyinterchanged with each other by means of the multiplexer in synchronismwith the clock pulses (see FIG. 5) (Steps 85 and 90 in FIG. 23).

Among the above-described control operations, the control operation foreach patient which is carried out in Step 85 is shown in the flow chartof FIG. 24. According to this flow chart, the output of each cooler 218is individually stepped down (Step 123) or up (Step 192) by one degreein accordance with need, whereby the temperature of cooling water iscontrolled such that the surface temperature is maintained at thepredetermined value (20° C.). The other operations of this embodimentare the same as those of the fourth embodiment (see FIGS. 18 and 19).

Since this embodiment is arranged and operates as described above, it ispossible to obtain advantageous effects which are substantiallyequivalent to those offered by the fourth embodiment. Since the coolers218 are individually provided for the patients, there is no interferencein terms of the temperature between the cooling water which is suppliedto one patient and that which is supplied to another. Accordingly,designing of the system is facilitated, and it becomes possible toeffect a precise control.

Seventh Embodiment

A seventh embodiment of the invention will be described hereinunder withreference to FIGS. 23, 25 and 26.

This invention aims at further accurately controlling the surfacetemperature of the body of each patient in addition to an object whichis similar to that of the sixth embodiment.

To this end, as shown in FIG. 25, a coolant temperature sensor 214 (onewhich is the same as that employed in the second embodiment serving as acoolant temperature detecting means which detects the temperature ofcooling water is additionally provided on the outlet side of the coolingmember 30 of each applicator 18, and information detected by eachcoolant temperature sensor 214 is delivered to the main control unit 16.The arrangement of the other portion of this embodiment is the same asthat of the sixth embodiment.

The following is a description of the general operation of thisembodiment. It is to be noted that target values for the internaltemperature and the surface temperature are respectively set at 43° C.and 20° C.

The control process for this embodiment is shown in the flow chart ofFIG. 23 which is described in relation to the sixth embodiment and inthe flow chart of FIG. 26. According to these control flow charts, thefollowing functions are added to those of the sixth embodiment.

(1) The main control unit 16 measures the surface temperature (Step 111in FIG. 26).

(2) A judgement is made as to whether or not the surface temperature ishigher than the set value (20° C.) (Step 121 in FIG. 26), and inaccordance with the result of this judgement, the output of the cooler218 concerned is stepped down (Step 123 in FIG. 26) or up (Step 192 inFIG. 26) by one degree through the corresponding cooling control circuit220. The other operations of this embodiment are the same as those ofthe sixth embodiment.

As described above, it is also possible according to this embodiment toobtain advantageous effects which are equivalent to those offered by thesixth embodiment. Even when the surface temperature of the heated regionundesirably fluctuates due to, for example, a change in the blood flowcondition in the body of a patient, the surface temperature iscontrolled such as to immediately return to the set value. It istherefore advantageously possible to reliably prevent the occurrence ofany thermal burn or the like and to alleviate pains which the patientmay suffer. Since the coolant flow paths are separately and individuallyallotted to patients, there is no interference in terms of temperaturebetween the cooling water supplied to one patient and that supplied toanother. Accordingly, it is possible to effect a more stable control.

It is to be noted that, although the number of patients who aresubjected to hyperthermia treatment is three in each of theabove-described embodiments, the number of patients may be increased. Insuch a case (e.g., the number of patients is five), it is only necessaryto change the clock pulse train shown in FIG. 5 into one such as thatshown in FIG. 28(1). By controlling or varying the period of this clockpulse train, it is possible to determine a microwave irradiation perioddefined between two adjacent internal temperature measuring periods.Accordingly, if the period of the clock pulse train is reduced, themicrowave irradiation interval is reduced correspondingly. It istherefore possible for an increased number of patients to besimultaneously subjected to hyperthermia treatment. Even in such a case,there is no hindrance to the treatment, since the internal temperaturemeasuring period (Δh) is also set such as to be an extremely shortperiod of time. Further, since the cost the magnetrons themselves isrelatively low, it is possible to minimize the increase in theinstallation cost even if the number of patients in increased.

What is claimed is:
 1. A heating apparatus for hyperthermia comprising:aplurality of electromagnetic wave generating means for generatingelectromagnetic waves, and respectively provided for a plurality ofpatients; a plurality of applicators respectively associated with thebodies of said patients; means for applying electromagnetic wavesgenerated by said electromagnetic wave generating means to respectiveones of said applicators for respectively irradiating the bodies of saidpatients with electromagnetic waves; a plurality of cooling membersrespectively associated with said applicators for cooling the bodies ofpatients with which the applicators are associated, each of said membershaving a coolant outlet side; coolant source means; means for supplyingcoolant from said source means to each of said cooling members; aplurality of coolant cooling means respectively provided for saidcooling members, each coolant cooling means being adapted to cool downthe coolant supplied to the corresponding one of said cooling members toa predetermined temperature; a plurality of internal temperaturedetecting means respectively associated with the bodies of said patientsfor detecting the temperature of a hyperthermia treatment region withina body irradiated with electromagnetic waves by the applicatorassociated with the body; a plurality of coolant temperature detectingmeans respectively associated with the cooling members, each of saidcoolant temperature detecting means being provided on the coolant outletside of the cooling member for detecting the temperature of coolantflowing out therefrom; and main control unit means responsive to saidinternal temperature detecting means for independently controlling theoperation of the respective electromagnetic wave generating means andthe respective coolant cooling means.
 2. A method for treating a regionof a patient with microwaves in a treatment branch, said methodcomprising the steps of:a) generating microwaves; b) applying thegenerated microwaves to a treatment region of a patient; c) cooling thesurface of said region using coolant that is cooled in a cooler whosecooling output is step-wise controllable; d) measuring the surfacetemperature of said region; e) reducing the output of the cooler by onestep if the surface temperature is less than a preset value, orincreasing the output of the cooler by one step if the surfacetemperature exceeds said preset value; and f) repeating steps c) throughe).
 3. A method according to claim 2 including the steps of:a) applyingmicrowaves to said region at a power level that is step-wisecontrollable for a first predetermined period of time after which thepower level is zero for a second predetermined period of time; b)measuring the internal temperature and surface temperature of saidregion while the power level is zero; c) increasing the power level byone step the next time microwaves are applied to said patient if themeasured internal temperature is less than a preselected value if andonly if the power level is less than a preselected value.
 4. A methodaccording to claim 3 including the step of beginning to time the heatingof said region when the measured internal temperature exceeds saidpreselected value, and terminating the application of microwaves to saidregion after a preselected period of time.
 5. A heating apparatus forhyperthermia comprising:a) a plurality of electromagnetic wavegeneration means for generating electromagnetic waves for treating aplurality of patients; b) a plurality of applicators, each of which isconnected to a different electromagnetic wave generation means, whereineach applicator comprises means for irradiating different patients withsufficient electromagnetic waves to treat tumors of said patients; c) aplurality of cooling members, each of which is attached to one of saidapplicators, for cooling the bodies of said patients with coolant, saidcooling members each having a coolant outlet and inlet, and wherein eachcooling member comprises means for recirculating the coolant throughsaid cooling members through their inlets and outlets; d) a plurality ofcoolers selectively operable for controlling the temperature of therecirculated coolant; e) a plurality of internal temperature detectingmeans, wherein each internal temperature detecting means comprises meansfor detecting the temperature of a hyperthermia treatment region withinthe body of a patient irradiated with electromagnetic waves by one ofsaid applicator; f) a plurality of coolant temperature detecting meanseach provided on the coolant outlet of each of said coolant members fordetecting the temperature of coolant flowing out therefrom; and g) amain control unit comprising means for: (1) receiving information fromsaid internal temperature detecting means; (2) controlling the output ofsaid electromagnetic wave generation means as a function of thetemperature detected by the plurality of internal temperature detectingmeans; (3) receiving information from said coolant temperature detectingmeans; and (4) selectively operating said coolers as a function of thetemperature of said coolant at the outlet side of said cooling members,wherein said main control unit, said plurality of cooling members, saidplurality of coolers, and said plurality of generation means andapplicators together comprise means for independently controlling thehyperthermia treatment of different patients.
 6. Apparatus according toclaim 5 wherein said control unit further comprises means forindependently controlling the irradiation of each patient withelectromagnetic waves by independently controlling the output ofelectromagnetic waves of each electromagnetic wave generation means. 7.Apparatus according to claim 6 wherein said control unit furthercomprises means for independently controlling the operation of eachcooler.
 8. Apparatus for treating a region of a patient using microwavescomprising:a) an applicator for irradiating a patient with microwaves;b) cooling means including a cooler for cooling coolant, a coolant loopfor exchanging coolant between the applicator and the cooler, and acooler control circuit for step-wise controlling the cooling output ofsaid cooler; c) means for measuring the surface temperature of saidregion; and d) a control unit having means responsive to said surfacetemperature for reducing the output of the cooler by one step if thesurface temperature is less than a preset value, or increasing theoutput of the cooler by one step if the surface temperature exceeds saidpreset value.
 9. Apparatus according to claim 8 including:a) means forapplying microwaves to said applicator at a power level that isstep-wise controllable for a first predetermined period of time afterwhich the power level is zero for a second predetermined period of time;and b) means for measuring the internal temperature of said region whilethe power level is zero; c) said control unit having means, responsiveto measuring said internal temperature for increasing the power level byone step the next time microwaves are applied to said applicator if saidinternal temperature is less than a preselected value if and only if thepower level is less than a preselected value.
 10. An apparatus accordingto claim 9 including timer means responsive to the internal temperaturefor beginning to time the heating of said region when the measuredinternal temperature exceeds a preset value, and terminating theapplication of microwaves to said applicator after a preselected periodof time.